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Article information
2017 , Volume 22, ¹ 1, p.17-24
Krutova I.Y.
Calculations of gas-dynamic parameters in the bottom part of tornado
Purpose. Numerical calculations for the special system of ordinary differential equations to determine gas-dynamic parameters of air currents in the bottom parts of tornadoes of various intensity. Methodology. Interpolating field observations for tornado of various intensity the Fujita scale is extended. For each class of tornadoes from the extended scale we use in situ observations of the wind speed and the width of the fracture line. For the chosen small value of the inflow radial velocity using numerical methods based on the Cauchy problem applied to the special system of ordinary differential equations, inflow radius was calculated for all types of tornadoes according to the extended Fujita scale. Thus calculated values of the velocities at the inflow radius must coincide with the field observations presented in the extended Fujita scale for all variants. Findings. 1. For the selected radius of the inflow and the inflow velocity values the wind speeds coincide with the calculated propagation velocity of the air at the inflow radius for all tornado classes of the extended Fujita scale. 2. The distributions of gas-dynamic parameters such as speed of sound, the radial and the tangential components of the gas velocity, are presented. Some of the results are presented in graphical form. 3. Instant streamlines that show the nature of the swirl for tornadoes of various intensity were calculated. Some results of calculations for the instant streamlines are also presented in the graphical form. 4. Analysis of the behavior for the modulus of air velocity allowed us to determine the numerical values of the radius for the distance from the sink, where the air flow rate is a specific fraction of its maximum value. Conclusions. The main parameters of the gas flow in the bottom part of the tornadoes of various intensities were determined. Radius of the area from which the air going into the vertical part is determined. The calculated flow agrees with the data of field observations of tornadoes of various intensity presented in the Fujita scale.
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Keywords: equations of gas-dynamics, Coriolis force, Fujita scale, gas twist
Author(s):
Krutova Irina Yuryevna
PhD.
Position: Head of Chair
Office: Snezhinsk Physical and Technical Institute National Research Nuclear University MEPhI
Address: 456776, Russia, Snezhinsk, str. Komsomolskaya, 8
Phone Office: (35146) 9-24-19
E-mail: IYKrutova@mephi.ru
SPIN-code: 5487-1414 References:
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Bibliography link:
Krutova I.Y. Calculations of gas-dynamic parameters in the bottom part of tornado // Computational technologies. 2017. V. 22. ¹ 1. P. 17-24
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